bg-image($url)
  background-image: url($url + "@2x.png")
  @media (-webkit-min-device-pixel-ratio: 3),(min-device-pixel-ratio: 3)
    background-image: url($url + "@3x.png")

border-1px($color)
	position:relative
	&:after
		display: block
		position: absolute
		left: 0
		bottom: 0
		width: 100%
		border-top: 1px solid $color
		content: ' '

border-none()
  &:after
    display: none

